Field of the Invention
The invention belongs to the field of food processing technology and, especially to the field of animal oil processing technology. Particularly, it relates to a method for producing high-quality lard or beef tallow with low cholesterol levels.
Background of the Invention
The self-sufficiency degree of China's edible oil is less than 40%, resulted in China's high dependency on foreign trade for edible oil. Finding new edible oil sources is an important way to alleviate China's oil supply security issues. China has abundant animal oil resources. According to statistics, China is the largest pork-producing country and the lard production is also No. 1 in the world. The production of beef tallow in China is one of the largest in the world as well. Therefore, the full development of animal oil resources like lard and beef tallow has great significance in solving the problem of insufficient self-supply of edible oil in China.
Lard is rich in nutrition, containing abundant saturated fatty acids and polyene alcohol, which are the main sources for human essential fatty acids and fat-soluble vitamins. It is also an important source for α-lipoprotein and arachidonic acid. Lard has unique flavor and can send out mouthwatering smell in the process of cooking. It can improve the smoothness of food texture when it is covered on the surface of the food during cooking. Moreover, lard is also an essential heat-transfer medium, which can increase cooking temperature, shorten cooking time and disperse unpleasant odor.
As an anther animal oil source, beef tallow has white color, abundant fatty acids and no undesirable flavor. Beef tallow is widely used in the food industry, such as bakery products (bread, biscuit, cake, etc.), shortening, margarine, frying oil, instant noodle, frozen foods, flavorings, etc.
Currently, dry method and wet method are the two main ways to produce animal oil, such as lard or beef tallow. In the dry method, lard or beef tallow is decocted from fat issue by high temperature, and is then squeezed and filtered to remove scraps. Because of the difficulty to control the temperature or long time of heating, the lard made of the dry method has problems such as darker color, increased acidity, higher degree of oxidation, and increased levels of malonaldehyde. The quality of lard and beef tallow made from this method is very low, needs refinery steps to obtain edible oil, and has very low yield. The wet method is to heat the fat tissue in the presence of water. The lard and beef tallow made of the wet method has large amount of moisture, poor flavor, easy to rancidity and high cholesterol levels (e.g. unrefined lard has an average cholesterol level of 100-150 mg/100 g, and refined lard still has an average cholesterol level of 50-70 mg/100 g). The above-mentioned disadvantages of the traditional processing methods have been a long-time problem that has limited the development and application of the animal oils.
Aqueous enzymatic extraction (AEE) is a new oil extraction technology that has been widely studied in recent years. The aqueous enzymatic method has many advantages, including high oil yields, white color of the final product, low energy consumption and low pollution. AEE has been applied in the extraction of many plant oils. However, there is no report about using AEE for the extraction of lard or beef tallow. There is a need to develop an AEE-based method for extracting animal oils. This invention satisfies this need and provides other benefits as well.